1. Field of the Invention
The present invention relates to a transport facility including a transport device configured to transport an article having a held portion to be held by holding means, along a transporting path with the article in a transporting attitude in which the held portion is located in a central part of the article in a fore and aft direction.
2. Description of the Related Art
Such transport facilities are used to transport articles along a transporting path by means of transport devices. By transporting an article in a transporting attitude in which the held portion (i.e., a portion to be held by a holding means) of the transported article is located in the central part in the fore and aft direction of the article, the articles can be held while maintaining a good balance in the fore and aft direction when holding the held portion of the transported article with the holding means. And, there is a conventional transport facility which transports FOUPs (Front Opening Unified Pod) as articles to be transported, each of which stores two or more substrates and is transported by a transport device within a factory with the fore and aft direction of each article oriented along the transporting direction. (See, for example, JP Publication of Application No. 06-156676.)
The transport facility described in this JP No. 06-156676 is used to transport FOUPs with a transport device; however, FOSBs (Front Opening Shipping Box) are sometimes transported by the transport device among the FOUPs. Although, like FOUPs, FOSBs are also used to store substrates, unlike the FOUPs, FOSBs are not standardized by a standard. And there are many FOSBs whose length (i.e. distance) from its held portion to one end potion along the fore and aft direction in its transporting attitude is longer than that of a FOUP. At times, only the FOSBs whose length (i.e. distance) from its held portion to one side end in the fore and aft direction in its transporting attitude is longer than that of a FOUP are used as the ones to be transported by the transport devices. And when transporting different kinds of articles whose lengths from the held portion to one end in the fore and aft direction in the transporting attitude differ from each other, such as when both FOUPs and FOSBs are transported by the transport devices, it is necessary to determine the kind of each of the different kinds of articles transported by the transport devices.
That is, the transport device described in JP No. 06-156676 detects the forward end portion of a FOUP transported to a stop preparation position with detection means, and stops the operation of the transport device to stop the FOUP at a stop position immediately after the forward end portion of FOUP is detected by the position detection means. When, on the other hand, this transport device transports a FOSB, the forward end portion of the FOSB would stop at the same position as the forward end portion of a FOUP if the operation of the transport device is stopped immediately after the forward end portion of the FOSB is detected by the position detection means. Thus, if a FOSB is stopped such that its forward end portion stops at the same position as the forward end portion of a FOUP, then the position of the held portion of the FOSB is displaced upstream in the transporting direction with respect to the position of the held portion of a FOUP by the difference in lengths from the held portion to one end portion along the fore and aft direction with respect to the transporting direction. Thus, there is a possibility that the held portion of the FOSB cannot be properly held by the holding means even when an attempt is made to hold the held portion of FOSB thus displaced by holding means.
To this end, when stopping a FOSB, it is conceivable to cause the held portion of the FOSB to stop at the same position as the held portion of a FOUP by stopping the operation of the transport device after a predetermined period has elapsed after the forward end portion is detected by the position detection means. However, to do so would require determining whether the article transported by the transport device is a FOUP or a FOSB before stopping the FOUP or the FOSB.
An example of a conventional device—for determining the kind of each of different kinds of articles whose lengths from the held portion to one end in the fore and aft direction in the transporting attitude differ from each other—includes one for which the articles to be transported include FOUPs that are transported with a lid attached and FOSBs that are transported without a lid and with which an article with a lid attached is determined to be a FOUP and an article without a lid is determined to be a FOSB based on the detected information from lid detection means. (See, for example, JP Publication of Application No. 2005-347576.)
This JP No. 2005-347576 describes a device for determining whether each of the different kinds of articles is a FOUP or a FOSB. And the device described in this reference distinguishes a FOUP (which has a lid attached) and a FOSB (which has no lid attached) from each other by detecting the presence of a lid by lid detection means. And if it's a FOUP, its lid is removed by a FOUP opener, and if it's a FOSB, the lid is not removed by the FOUP opener since it had already been removed manually in advance. However, a lid is typically attached when transporting either a FOUP or a FOSB by a transport device. Thus, in the case where a lid is attached to both the FOUPs and FOSBs, it is not possible to tell them apart with the device described in this reference.
Therefore, it is not possible to determine the kind of each of different kinds of articles with the device described in this reference when transporting different kinds of articles whose lengths from the held portion to one end in the fore and aft direction in the transporting attitude differ from each other.
It is conceivable to have a device—for determining the kind of each of different kinds of articles whose lengths from the held portion to one end in the fore and aft direction in the transporting attitude differ from each other—for which FOUPs (which have a flange portion that is located on the top surface and that is gripped when supported and suspended by a ceiling transport vehicle) and FOSBs (which have no such flange portion) are transported by a transport device, and with which an article with a flange portion is determined to be a FOUP and an article without a flange portion is determined to be a FOSB. However, there are also FOSBs that have a flange portion; therefore, it is not possible to distinguish the FOUPS from the FOSBs when transporting FOSBs having such a flange portion among FOUPs with the transport device.